Method and apparatus for automatically sewing along the contoured edge of a fabric workpiece



April 16, 1968 c SZENTKUTI ET AL 3,377,967

METHOD AND APPARATUS FOR AUTOMATICALLY SEWING ALONG THE CONTOURED EDGE OF A FABRIC WORKPIECE Filed June 2, 1966 V N m 3 Sheets-$heet 1 .IIIIIIIIIIILL INVENTOR. CHARLES SZENTKUTI DOUGLAS G. NOILES BY 2% M 5% ATTORNEYS.

April 16, 1968 Q szE u-n ET AL 3,377,967

METHOD AND APPARATUS FOR AUTOMATICALLY SEWING ALONG THE CONTOURED EDGE OF A FABRIC WORKPIECE 3 Sheets-Sheet 2' Filed June 2, 1966 INVENTOR. CHARLES SZENTKUTI DOUGLAS G. NOlLES ATTORNEYS.

April 16, 1968 c, szE u ET AL 3,377,967

METHOD AND APPARATUS FOR AUTOMATICALLY SEWING ALONG THE CONTOURED EDGE OF A FABRIC WORKPIECE Filed June 2, 1966 v 3 Sheets-Sheet 5 INVENTOR. CHARLES SZENTKUTI DOUGLAS 6. NOILES 7 BY Z 1 W TTORIVEYS.

United States Patent 0 3,377,967 METHOD AND APPARATUS FOR AUTOMATI- CALLY SEWING ALONG THE CONTOURED EDGE OF A FABRIC WORKPIECE Charles Szentkuti, Ridgefield, and Douglas G. Noiles,

New Qanaan, Conn., assignors, by mesne assignments, to Ivanhoe Research Corporation, a corporation of Delaware Filed June 2, 1966, Ser. No. 554,884 12 Claims. (Cl. 112-2) This invention relates to method and apparatus for automatically sewing along the contoured edge of a fabric workpiece. The invention has special application to the forming of overedge or serging stitching along the irregularly contoured edge of a fabric workpiece but is useful also for automatically sewing other types of stitches along a line adjacent to an irregularly contoured edge, the sewing and workpiece guiding being done Without an operators manual assistance. The invention also can be used to advantage when sewing two congruent curved pieces together by serging or by other types of stitching.

Summary In the manufacture of garments, clothing, headgear, footwear, home furnishings, and the like, the completed work is often assembled from fabric workpieces which contain irregularly contoured edges along which sewing is applied. These are of various sizes, shapes and lengths. In order to form the stitches properly along such an irregularly contoured edge, that is, to form the stitches neatly, of uniform length and uniformly spaced from the edge so as to be durable and attractive for commercial acceptance, two operating conditions must be satisfied at all times during the sewing: (1) The fabric workpiece and sewing machine needle must be guided relative to each other such that the stitches are of uniform length and uniformly spaced from the edge, and (2) the direction of the sewing machine sewing alignment must generally be kept tangent to the edge of the goods at each instant, that is, the edge must always be approaching the needle from directly in front.

rior to the present invention attempts have been made to provide a sewing machine which would accomplish this contoured edge sewing. One prior system advanced the cloth longitudinally and moved it laterally so as to cause the edge of the workpiece to pass over a given work point relative to the centerline of the point of penetration of the needle. The whole sewing machine itself was pivotally mounted to rotate about the centerline of the needle so as to maintain the sewing direction of the machine at each instant in alignment with the tangent to the contoured edge. This prior system was complex and expensive, requiring mechanism for moving the fabric in two directions plus mechanism for turning the whole machine about the centerline of the needle plus control equipment for all of these moving parts.

Another prior machine advanced the work longitudinally at a constant rate. The sewing machine itself was movably mounted so as to move the machine laterally to follow the contoured edge to keep the centerline of the needle uniformly spaced from the edge, and the sewing machine was also pivotally mounted to rotate about the needle centerline to maintain tangential alignment. This prior system was also complex and expensive requiring elaborate control mechanism to move and to rotate the machine in accordance with the instantaneous position and tangency of the contoured edge.

The present invention enables a stationary sewing machine to be used. The contoured edge of the cloth guides itself and is caused to move and to turn so that each instant it is moving tangent to the desired direction.

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In accordance with the invention the workpiece is conveyed along a path past a sewing station with the main body of the piece being restrained and the contoured edge bein free and being positioned beyond a predetermined line in the path. The contoured edge is separately controlled to move it along tangent to said line while allowing an unrestrained and therefore flexible portion of the body of the workpiece to buckle up to accommodate any pile-up of cloth resulting from such edge control, and the cloth is sewn at a position on said predetermined line in said work zone. The contoured edge may be either concave or convex and may include various concave and convex portions.

The way in which the contoured edge is controlled is to guide it in a direction toward the body of the piece, while the feed dogs of the sewing machine are driven at an effective rate of advance which exceeds the rate of conveying the body of the piece by a small amount of the order of O to 10%. The resultant overfeeding of the very edge pulls it against the guide as the edge advances. These steps cause the contoured edge to move and to turn so that at each instant it is moving tangentially to the predetermined line on which the sewing is applied. Thus, the desired sewing along the contoured edge is applied neatly, durably and reliably at high speed without an operators manual assistance.

In this specification and in the accompanying drawings are described and shown method and apparatus for automatically sewing along the contoured edge of a fabric workpiece, the illustrative embodiments as shown being the best mode now contemplated by us for carrying out the invention. It is to be understood that these illustrations are not intended to be exhaustive nor limiting of the invention but on the contrary is given so that those skilled in the art will fully understand the invention and will appreciate how the examples as described can be adapted and modified to meet the conditions of a particular application.

The various objects, aspects and advantages of the present invention will be more fully understood from a consideration of the following description in conjunction with accompanying drawings.

Description FIGURE 1 is a side elevational view of a system for performing the method of sewing along the contoured edge of a fabric workpiece;

FIGURE 2 is a plan view showing the workpiece being conveyed past the sewing station;

FIGURE 3 is an enlarged plan view of a portion of the sewing station as seen in FIGURE 2 with the contoured edge of the workpiece approaching the needle;

FIGURE 4 is similar to FIGURE 3 showing the sewing progressing along the contoured edge; and

FIGURES 5 and 6 are enlarged detailed cross-sectional views taken along the lines 55 and 66, respectively, of FIGURE 4, showing the controlled buckling of the fabric.

As used herein the term workpiece is intended to include individual pieces as well as sub-assemblies or semifinished goods including two or more pieces or components secured together. The term fabric is intended to include woven goods, cloth, textiles, and also nonwoven or felted, or perforate goods having a fabric-like character suitable for use in clothing, garments, headgear, footwear, home furnishings and similar uses, regardless of whether the material of the goods is in one layer or multiple layers and regardless of whether the goods are natural, synthetic or blended.

As shown in the drawings to which reference will now be made in detail, a workpiece W is conveyed by a wide conveyor belt along a path 12 extending past a sewing station 14. The workpiece W is in the form of a fabric panel which has been cut in a shape to be used in fabricating mens pants so that it has a contoured cut outsearn edge 16 and a contoured cut inseam edge 18. To finish on the contoured inseam edge 18, an overedge stitching, called a serging, is applied along this edge by means of a conventional serging sewing machine 28. A similar serging is applied along the contoured edge 16 by another system similar to the present one. The overedge stitching or serging is indicated in FIGURES 4 and 6 by the reference S.

The main body of the piece W is carried along by the conveyor belt 10. The conveyor belt surface provides a high friction with the piece W to restrain this workpiece, as for example by a canvas conveyor belt 16. Additional riction and restraint between the belt and workpiece are created adjacent to the sewing area by stationary restraining shoe means 21 which rides upon the main body of the workpiece as it is translated past the sewing station 14. This shoe 21 includes a wide resilient strip 22 having a slippery lower surface pressing down on the piece W.

As seen in FIGURE 2, the contoured edge 18 is free of restraint and is positioned so that the edge 18 plus an adjacent fabric portion 23 extend beyond the edge of the belt 10. This contoured edge 18 extends beyond a predetermined line L (FIGURE 2) in the workpiece path, this line L being directly aligned with stitching point P (FIGURES 3 and 4) at which the needle N passes through the workpiece material during sewing.

The edge 18 and the adjacent portion 23 are controlled in position separately from the main body of the workpiece W. As shown in FIGURES 3, 4 and 5 the edge 18 slides against a fixed cam guide 24 and travels beneath a fixed top plate 25 which is transparent to enable an inspector to observe the edge 18 from time to time as it slides along the cam 24 and also to enable a photocell sensing unit 26 (FIGURES 1 and 2) to sense the approach of the leading end of the piece W. This control unit 26 is mounted upon an elevated support bar 27, and it starts the sewing machine when the leading end of the workpiece is still approximately three inches away from the stitching point P. This control unit 26 comprises first control means actuated in response to the approaching workpiece.

A second control means actuated in response to the approaching workpiece includes an elevated miniature lamp 28 mounted upon a second support bar 29, and this lamp is beamed down toward a photocell 30 which is positioned beneath the path of the workpiece. This second control means 28, 30 is positioned approximately A. of an inch from the stitching point P to actuate a conventional thread cutting unit for cutting the chain of airborne stitches being formed by the machine 20. These airborne stitches are drawn into a suction tube 31 which has its inlet positioned closely adjacent to the needle N. Additionally, there is an air nozzle J positioned to blow on the airborne chain to cause the chain to move to the desired location relative to a cutting knife mechanism 32 (FIG. 3). This type of knife mechanism 32 is available commercially from Clinton Industries of Hackensack, NJ. as No. CC115NS and from American Attachment Company of Fall River, Mass. as the Autotrim cutter. It is located between the needle N and the mouth of the suction tube 31. The air flow from the nozzle I also strikes the needle N and serves to cool it by carrying away the heat of friction generated by the sustained high cyclic rate of needle penetration of the workpiece.

This sequence of operation produces a chain of airborne interlocking stitches when the machine 20 begins running. These airborne stitches are captured by the suction action of the tube 31 so that they are drawn into the tube and are placed under tension. This sequence of operations assures that the stitches are being suitably formed under tension before the leading end of the edge 18 is engaged. Then, just before this edge is engaged, the tail of stitches is cut off by actuation of the control 28, 38 so that only a short neat end remains. The tube 31 is arranged to dispose of the cut thread without clogging.

The edge 18 is positioned beyond the line L so that it engages against the cam 24 which pushes the edge inwardly toward the main body of the workpiece W to bring the advancing edge 18 into alignment with the needle N. The unrestrained flexible portion 23 buckles up (FIGURE 5) to accommodate the lateral pile-up of fabric material. This edge 18 and free adjacent portion 23 are slidingly supported by supporting means 34 provided by a worktable mounted upon a base frame 36 and legs 33.

It is noted that the top plate 25 is spaced above the support surface 34 by a small distance only slightly greater than the thickness of the workpiece portion 23. Thus, the edge 18 is controlled in the vicinity of the stitching point P to prevent buckling of the edge on which the sewing machine is working. The edge of the top plate 25 slopes upwardly and inwardly at 41) (FIGURE 5) and fairs into a guide cover 41 which controls the shape of the buckling of the fabric portion 23 to assure that it rises up and inward without toppling over upon the top plate 25. This guide cover 41 converges upwardly toward an inner wall guide 42 extending upwardly against which the excess material is piled up.

The wall guide 42 is secured to the side of the shoe structure 21, and it has a downstream end 43 which curves and slopes outwardly and downwardly so as to cam the excess material outwardly and downwardly to lie flat again upon the support surface 34. The support surface 34 is made as slippery as possible in the vicinity of the guide end 43 to facilitate the lying fiat of the fabric portion 23.

The sewing machine 28 includes conventional reciprocating feed dogs which intermittently engage the underside of the workpiece along the edge 18. These dogs pull fabric forward during the respective moments when the reciprocating needle N is withdrawn from the fabric. Even though the whole body of the workpiece W is continuously moving, the very edge 18 is stationary during the time when the needle N is penetrating the fabric.

In order to control the edge 18, the intermittent feed dogs are driven at a feed rate which somewhat exceeds the feed rate of the conveyor belt 10 by a small amount of the order of 0 to 10%. This places the edge portion 23 of the fabric material under localized tension near the cam guide 24 pulling outwardly as indicated at a (FIG- URE 4) so as to hold the edge 18 firmly against the cam guide 24 at all times regardless of whether the contour of the edge 18 is curving outwardly or inwardly or contains successive curves in different directions.

It is noted that this method and apparatus are not intended to track past a sharp cusp. Thus, in FIGURE 2 the serging stitches leave the edge 18 at the end point E and are suitably cut off thereafter by a sensing photocell control unit (not shown) and then the machine 20 is stopped to await the next workpiece.

In this system the sewing machine 20 is driven at a rate of 5,400 or more stitches per minute or more stitches per second). When it is desired to form ten stitches per inchthe conveyor belt 10 is traversed at a ratet of 9 inches per second; conversely, when it is desired to form five stitches per inch the conveyor belt 10 is traversed at a rate of 18 inches per second, and so forth. The effective feed dog rate somewhat exceeds the traverse rate of the belt by a small differential amount lying within the range from 0 to 10%, depending upon the particular fabric being handled. The precise differential in feed rates depends upon the characteristics of the fabric in the edge 18 and adjacent portion 23 of the Workp-iece W and is determined by trial. Generally, the feed rate differential is larger for fabric which has a greater lateral extensibility, because it requires increasedpulling to obtain the desired localized tension.

In order to provide increased pressure and restraint upon the main body of the workpiece in the vicinity of the sewing point P, the shoe'structure 21 includes a second resilient strip 22'pressing down upon the central part of the longer strip 22.

There is a cut out 44 (FIGURES 2, 3, 4) in the work support table 34 to provide room for the sewing machine 20. In operation the machine 20 remains stationary in its inner position shown in FIGURE 2 in the sewing station 14. The machine 20 is mounted on a support plate 46 slidably held by a pair of ways 48 secured to the base frame 36. Thus, the machine 20 can be slid outwardly from its sewing station along the ways 48 to provide access for rethreading and servicing the machine.

The conveyor belt moves along upon a plurality of polished hardwood slats 50 secured to frame 36 and forming a low-friction support bed for the belt 10. These slats are spaced apart beneath the ,belt 10 and are tightly adjacent to form the slippery support surface 34 beneath the extending unrestrained edge 18 andportion 23.

The conveyor belt 10 is tensioned by an adjustable roller 52 and is driven by a roll 54 which is powered through a belt 55 driven by an electric motor and gear box 56 mounted on frame 36. It will be understood that the conveyor belt 10 travels around idler rollers positioned at opposite ends of the table slats'50.

In FIGURE 2 the line L is a line which is shown for purposes of explanation extending through the sewing point P and being parallel with the direction of travel of the belt 10. The line R is a register line actually drawn on the table 34 in a direction parallel to the belt travel and which passes tangent to the inner limit of the cam guide 24. In operation the main body of the workpiece W is initially placed upon the conveyor belt 10 in such a way that all of the contoured edge 18 is positioned on or beyond the register line R, regardless of whether this edge 18 is concave or convex or includes segments of both kinds of curves. Thus, all of the edge 18 will engage the cam 24 to be controlled by the cam so as to be brought into proper relationship with the sewing machine. The register line R is only slightly offset from a line L passing through the sewing point P by an amount equal to the distance that the point of penetration is to be spaced from the very edge 18 of the workpiece.

The distance from the edge of the conveyor belt 10 to the line L lies in the range from /8 to 3 inches depending upon the compliance of the workpiece material. This distance is smaller when handling more compliant material.

The sewing machine is driven through a timing belt 58, pulley sheaves S9 and belt 60 which is powered through an electromagnetic clutch and brake unit 62, in turn being driven by a belt 64 running from the main electric motor drive 56. This clutch and brake unit 62 is controlled as described above to start and stop the machine 20, while the main drive 56 continues running and the belt 10 continues translating.

It will be appreciated that instead of serging other types of sewing can be utilized, including one needle or two needle stitching of the lockstitch type by virtue of the fact that the edge of the workpiece is controlled to approach the needle or needles from the proper direction in front.

The terms and expressions which we have employed are used in a descriptive and not in a limiting sense, and we have no intention of excluding such equivalents of the invention described as fall within the scope of the claims.

What is claimed is:

1. A method of stitching along the edge of a fabric workpiece having a contoured edge to be so stitched comprising:

(a) conveying said workpiece along a path through a sewing station with the main body of the piece being restrained and said contoured edge being free and being positioned beyond a predetermined line in the workpiece path,

(b) separately controlling said contoured edge to move it in a direction along said line in said sewing station while allowing an unrestrained and flexible portion of the body of said work-piece to buckle up to accommodate any pile-up of cloth resulting from such edge control, and

(c) stitching said contoured edge at a position on said line in said sewing station.

2. The method according to claim 1 in which said contoured edge is controlled in said sewing station by slidingly camming said edge inwardly toward said main body and laterally tensioning said edge as it passes near said sewing position.

3. The method according to claim 2 in which said edge is laterally tensioned by intermittently feeding the edge forward at a rate exceeding the rate of advance of the main body of the workpiece.

4. The method as claimed in claim 1 and wherein the buckling fabric portion is (d) guided inwardly and upwardly, and

(e) following stitching the buckling portion is guided outwardly and downwardly to cause the sewn edge and adjacent fabric portion to move out and down into its original relationship with respect to the main body of the workpiece W.

5. A method according to claim 4 and wherein (f) the contoured edge itself is guided to prevent buckling thereof as it advances toward the sewing position.

6. A system for stitching the contoured edge of a fabric workpiece comprising:

(a) a work supporting surface having a conveyor belt running along near the portion of the surface thereof against which the main body of said fabric workpiece is to be conveyed,

(b) a means for restraining the main body of said workpiece as it is conveyed,

(c) edge control means associated with said table surface and near to an edge of said belt including (d) a fixed edge guiding member at a predetermined position relative to said belt slidingly engaging said edge and camming it inwardly, and

(e) an edge stitching machine positioned adjacent said edge control means to stitch along said contoured edge as it is being moved past said edge control means.

7. A system as claimed in claim 6 in which said edge control means includes (f) guide means for upwardly guiding a buckling portion of said workpiece intermediate said contoured edge and said main body.

'8. A system as claimed in claim 7 in which said edge control means includes (g) outward guide means engaging said buckling portion after the stitches have been formed for moving the edge laterally outwardly.

9. A system for stitching the contoured edge of a fabric workpiece as claimed in claim 6 in which said conveyor belt has a high friction surface and said means for restraining the body of the workpiece presses the workpiece firmly against said high friction surface of 65 the belt.

10. A process of automatically sewing along the contoured edge of a fabric workpiece comprising the steps of:

(a) translating the workpiece along a path past a sewing station,

(b) projecting the contoured edge at all points along its length beyond a predetermined line in the path,

(c) restraining the main body of the workpiece to prevent buckling while the contoured edge and adjacent portion of the fabric are free to buckle,

(d) guiding the contoured edge which projects beyond said line toward said line as said edge approaches the sewing station while causing the adjacent portion of the workpiece to buckle to accommodate the pile up of the workpiece resulting from said guiding,

(e) sewing the workpiece along near said edge as said edge moves along near said line, and

(f) after the edge leaves the sewing station allowing the edge to move out beyond said line to flatten the buckled portion of the cloth.

11. A system for stitching the contoured edge of a fabric workpiece comprising:

(a) a sewing station,

(-b) means for moving the workpiece relative to said sewing station,

(c) means for restraining the main body of the workpiece as it is being moved while allowing the contoured edge and adjacent edge portion of the workpiece to be free to buckle up,

(d) a cam guide engaging the contoured edge in front of the sewing station, said cam guide converging inwardly toward the main body of the workpiece guiding the contoured edge into alignment with the sewing station, and

(e) feed means engaging the edge portion of the fabric and placing the edge portion under localized tension near said cam guide pulling the edge portion against said cam guide.

12. A system for stitching the contoured edge of a fabric workpiece as claimed in claim 11 wherein said feed means are feed dogs in the sewing station driven at a feed rate somewhat exceeding the rate of movement of the main body of the workpiece, and having cover means between said cam guide and said restraining means for guiding the fabric which buckles therebetween.

References Cited UNITED STATES PATENTS 2,797,656 7/1957 Reid 1l2-2 3,182,619 5/1965 Sally 112-153 XR 3,296,986 1/1967 Gansl. 3,322,081 5/ 1967 Winberg.

JORDAN FRANKLIN, Primary Examiner.

I. R. BOLER, Assistant Examiner. 

6. A SYSTEM FOR STITCHING THE CONTOURED EDGE OF A FABRIC WORKPIECE COMPRISING: (A) A WORK SUPPORTING SURFACE HAVING A CONVEYOR BELT RUNNING ALONG NEAR THE PORTION OF THE SURFACE THEREOF AGAINST WHICH THE MAIN BODY OF SAID FABRIC WORKPIECE IS TO BE CONVEYED, (B) A MEANS FOR RESTRAINING THE MAIN BODY OF SAID WORKPIECE AS IT IS CONVEYED, (C) EDGE CONTROL MEANS ASSOCIATED WITH SAID TABLE SURFACE AND NEAR TO AN EDGE OF SAID BELT INCLUDING (D) A FIXED EDGE GUIDING MEMBER AT A PREDETERMINED POSITION RELATIVE TO SAID BELT SLIDINGLY ENGAGING SAID EDGE AND CAMMING IT INWARDLY, AND (E) AN EDGE STITCHING MACHINE POSITIONED ADJACENT SAID EDGE CONTROL MEANS TO STITCH ALONG SAID CONTOURED EDGE AS IT IS BEING MOVED PAST SAID EDGE CONTROL MEANS. 